Regulation of morphological and functional properties of astrocytes by hydrogen peroxide

Effects of hydrogen peroxide on morphological characteristics, proliferation index, and menadione-dependent lucigenin-enhanced chemiluminescence of C6 glioma cells were studied. It was established that H₂O₂ at 5 × 10^?7?1 × 10^?8 M concentrations acted as a regulator of morphological and functional properties of astrocytes, inducing their reactivation, which is manifested as cell body hypertrophy and an increase of proliferative activity and menadione-induced production of superoxide anion radicals (O ₂ ^?? ). Cytodestructive action of hydrogen peroxide at a concentration higher than 1 × 10^?6 M on C6 glioma cells shows itself as a decrease of their proliferation index and the ability to generate O ₂ ^?? under the effect of menadione. Use of lipopolysaccharide B as a functional stimulator has shown that H₂O₂ modifies signaling pathways leading to an increase of mitotic activity of C6 glioma cells and decreases the yield of lucigenin-dependent chemiluminescence of astrocytes under the action of menadione to the level of control values.     

Physiological Heterothallism and Sexuality in Euascomycetes: A Partial History

Copyright 1998 Academic Press.     

Effect of hydrogen peroxide on ability of neutrophils to generate the reactive oxygen and chlorine species and secrete myeloperoxidase in vitro

The influence of H2O2 at concentrations of 10(-8)--10(-2) mol/l on neutrophil ability to generate the reactive oxygen and chlorine species (ROCS) and secrete myeloperoxidase (MPO) was studied, and H202 injurious effect on neutrophils was also investigated in this work. It was revealed that H2O2 at concentrations of 2 x 10(-3)--2 x 10(-2) mol/l induced disturbance of the neutrophil membrane barrier properties and lactate dehydrogenase release. The incubation of the neutrophils with the addition of 10(-4)--10(-7) mol/l H2O2 led to an increase in the cell ability to generate ROCS during phagocytosis and decreased neutrophil ability to secrete MPO and ROCS in extracellular medium during adhesion. The mechanisms of H2O2 effect are coupled with arachidonic acid metabolism. Inhibition of metabolic pathways of 5-lipoxygenase or cyclooxygenase increased the destructive effect of H2O2 on the cells. Five-lipoxygenase way prohibition led to cancellation of H2O2 influence on MPO and ROCS secretion and to enhancement of H2O2 effect on neutrophil ability to generate ROCS during phagocytosis. The data obtained testify to the high neutrophil resistance to destructive effect of H2O2 and confirm the regulatory role of H2O2 with respect to the neutrophil functions.     

Orthologous gene-expression profiling in multi-species models: search for candidate genes

Microarray-driven gene-expression profiles are generally produced and analyzed for a single specific experimental model. We have assessed an analytical approach that simultaneously evaluates multi-species experimental models within a particular biological condition using orthologous genes as linkers for the various Affymetrix microarray platforms on multi-species models of ventilator-associated lung injury. The results suggest that this approach may be a useful tool in the evaluation of biological processes of interest and selection of process-related candidate genes.     

Regulation of morphologicaland functional properties of astroglial cells by hydrogen peroxide

Effects of hydrogen peroxide on morphological characteristics, proliferation index, menadione-dependent lucigenin-enhanced chemiluminescence of C6 glioma cells were studied. It was established that H2O2 at 1 x 10(-8) - 5 x 10(-7) M concentrations acts as a regulator of morphological and functional properties of astrocytes by inducing their reactivation that is manifested as a cell body hypertrophy and an increase of proliferative activity and of menadione-dependent production of superoxide (O2- ). Cytodestructive action of hydrogen peroxide at a concentration higher than 1 microM on C6 glioma cells shows itself as a decrease of their proliferation index and the ability to generate O2- under menadione action. Using lipopolysaccharide B as a functional stimulator it has been shown that H2O2 modifies signaling pathways leading to the increase of mitotic activity of C6 glioma cells and decreases the yield of lucigenin-enhanced chemiluminescence of astrocytes under menadione action to the level of control values.     

2‐Hexadecenal inhibits growth of C6 glioma cells

2‐Hexadecenal (2HD) formation in the organism occurs via irreversible enzymatic degradation of sphingosine‐1‐phosphate or nonenzymatic γ‐, UV‐, or HOCl‐induced destruction of a number of sphingolipids including S1P. The current research focuses on the study of 2HD effects on C6 glioma cells growth. The results obtained show that 2HD causes a dose‐dependent decrease in proliferative and mitotic indices. The change in the mitotic index is due to the redistribution of cells in the different phases of mitosis. These processes are accompanied by cytoskeleton rearrangement and changes in cell morphology, which are expressed in F‐actin redistribution, change in the number and type of filopodia and fibrils, leading to cell shape changes, decrease in intercellular contacts and monolayer rarefaction. Cells treatment with 2HD leads to apoptosis induction and signalling pathways modification, including activation of JNK, p38, and ERK1/2 MAPK but not PI3K. The effects observed are not related to the cytotoxicity of 2HD. Significance of the study: 2HD—an unsaturated aldehyde, which level can rise under conditions of oxidative stress as a result of nonenzymatic sphingolipids' destruction. The mechanisms of 2HD action on various cell types have not been sufficiently studied. Therefore, the study on functional role of this aldehyde in different cell types that may be its target is relevant. This study demonstrated that 2HD inhibits growth of C6 glioma cells due to modification of intracellular processes of signal transduction, cytoskeleton rearrangement, change in the mitotic regimen and apoptosis induction.     

Expression of Toll-like receptor 2 is up-regulated in monocytes from patients with chronic obstructive pulmonary disease

Background

Chronic obstructive pulmonary disease (COPD) is characterised by pulmonary and systemic inflammation which flare-up during episodes of acute exacerbation (AECOPD). Given the role of Toll-like receptors (TLRs) in the induction of inflammatory responses we investigated the involvement of TLRs in COPD pathogenesis.

Methods

The expression of TLR-2, TLR-4 and CD14 in monocytes was analyzed by flow cytometry. To study the functional responses of these receptors, monocytes were stimulated with peptidoglycan or lipopolysaccharide and the amounts of TNFα and IL-6 secreted were determined by ELISA.

Results

We found that the expression of TLR-2 was up-regulated in peripheral blood monocytes from COPD patients, either clinically stable or during AECOPD, as compared to never smokers or smokers with normal lung function. Upon stimulation with TLR-2 ligand monocytes from COPD patients secreted increased amounts of cytokines than similarly stimulated monocytes from never smokers and smokers. In contrast, the expressions of TLR-4 and CD14 were not significantly different between groups, and the response to lipopolysaccharide (a TLR-4 ligand) stimulation was not significantly different either. At discharge from hospital TLR-2 expression was down-regulated in peripheral blood monocytes from AECOPD patients. This could be due to the treatment with systemic steroids because, in vitro, steroids down-regulated TLR-2 expression in a dose-dependent manner. Finally, we demonstrated that IL-6, whose plasma levels are elevated in patients, up-regulated in vitro TLR-2 expression in monocytes from never smokers.

Conclusion

Our results reveal abnormalities in TLRs expression in COPD patients and highlight its potential relationship with systemic inflammation in these patients.

     

Isolation and structural and functional characterization of two stable peptic fragments of human alpha-fetoprotein.

Short-time limited peptic hydrolysis of ligand-free human alpha-fetoprotein (AFP) gave two main fragments with molecular masses of 38 and 32 kDa, which had been produced by splitting of the molecule at the position Leu(312)-Asn(313). A more prolonged proteolysis led to the further degradation of these fragments and appearance of highly proteolytically resistant 23-kDa (P23) and 26-kDa (P26) fragments, corresponding to N- and C-terminal parts of the AFP molecule, respectively. Comparative study of intact free of ligands AFP and isolated stable P23 and P26 fragments by circular dichroism, differential scanning calorimetry, and immunoprecipitation techniques demonstrated that these fragments conserved native secondary, tertiary; and antigenic structure, characteristic of the intact molecule. It was concluded that, free of ligands, the AFP molecule could be considered as a three-domain molecule, in which two compact rigid domains (N-terminal domain I and C-terminal domain III) are connected by relatively labile domain II. The structure of domain II could be approximated by a "molten globule" state, characterized by the absence of rigid tertiary structure but having a pronounced secondary structure. Tumor-suppressive activity via induction of apoptosis was recently shown for AFP [Dudich, E. I., et al. (1998) Tumor Biol. 19, 261-272]. We studied here the ability of isolated proteolytic AFP fragments to induce apoptosis in the AFP-sensitive Raji cell line, to determine possible localization of the active site responsible for apoptosis signaling. Unlike intact AFP, neither isolated fragments nor their equimolar mixture was able to induce apoptosis in a human lymphoma Raji cell line. However, it was demonstrated that both fragments P23 or P26 and their equimolar mixture P23 + P26 operated synergistically with intact AFP in suppression of Raji cell proliferation. These data suggested that two structurally determined requirements are necessary for AFP-mediated triggering of apoptosis: (i) dimerization of AFP to form the heterodimeric complex of C- and N-terminal domains and (ii) participation of the central part of AFP molecule (domain II).